1. Field of the Invention
The present invention relates to a method for structuring a flat substrate consisting of a glass-type material.
2. Description of the Prior Art
As a material in modern microelectronics or micro-mechanics, glass or glass-type materials have numerous advantages over other materials, in particular over plastics, with regard to their low thermal expansion coefficients, which compare to those of semiconductor materials, and moreover they possess great mechanical and chemical stability. As a result these materials have acquired considerable significance in many technical fields.
However, there are major limitations in the production especially of technically interesting products, in particular of micro-mechanical and microelectronic components of glass as hitherto there are only less suited etching processes available for micro-structuring glass. Consequently, presently only mechanical processes such as sawing, grinding, polishing, scratching, ultrasound or sand blasting are employed. As a result, the structuring possibilities of glass are greatly limited. With these conventional processing methods, however, it is impossible to structure glass in the micrometer and, in particular, in the sub-micrometer range with the necessary precision required in semiconductor component technology.
Due to these major structuring limitations, plastic is used in all presently known methods to fabricate micro-structural bodies. For instance, DE 43 07 869 A1 describes a method in which the micro-structural body is molded in plastic or in sinter materials by means of a mold insert. The micro-structured mold insert is made of a solid body consisting of metal, ceramic, glass, stone or mono-crystalline material by means of fine precision mechanical processing, additive or substractive structuring. Then the mold insert is filled with a free-flowing material, covered and after hardening, the material is separated from the mold insert. The micro-structural body fabricated in this manner has, however, also the drawback that it is made of a material which has a high thermal expansion coefficient and possesses, compared to glass-type materials, little mechanical and chemical stability.
WO 97/19027 A1 describes a base substrate with a trough structure into which the biological sample material is placed and a method for the production thereof. In order to structure the base substrate, it is heated in such a manner that it can be easily molded and upon reaching the required temperature, a stamp unit, which consists of a non-deformable material, is applied to the base substrate. Then the base substrate is cooled and the stamp unit is removed. Although base substrates of glass-type materials can also be molded with the method described here, a combination of arbitrary regions of glass and of silicon on one and the same support, according to the locally required properties, cannot be obtained with this method either.
A breakthrough regarding the technical limitations of working with glass would open new fields of application in which composite materials of silicon and glass would play a major role. Such composite elements could exploit the complementary properties of both materials. For example, compared to silicon, glass possesses very low electric and thermal conductivity but, contrary to silicon, is optically transparent in the visible wavelength range.
Moreover, in addition to silicon, glass or glass-type materials play an important role in the realization of micro-mechanical components. In particular, with regard to encapsulating components, glass is often employed as an electrically insulating material. But here too, micro-structuring faces the above described limitations.
With the prior art methods, it is impossible to produce an intimate structure made of a semiconductor, for example silicon and glass, whose geometry can be freely dimensioned laterally in the micro range and sub-micro range. However, this would be desirable in order to be able to combine arbitrary regions of glass and silicon on one and the same support and, in particular, in order to dimension them according to the locally required properties.